The foundations for API 650 larger diameter tanks

The inner and outer tanks may be decoupled for seismic design of the tank and anchorage and assumed to act independently. However, if the inner and outer tanks API 650 larger diameter tanks are supported by a common foundation, the seismic foundation loading shall be calculated using the lesser response modification values for either the inner tank or outer tank for both tanks and a dynamic analysis shall be performed to determine the combined effect.
Allowable Stresses: For Appendix R tanks, design allowable stresses shall be per API 620 large low pressure storage tank, Section R.3.3.

This specification, in conjunction with API 650 Standard, prescribes minimum standards for the API 650 larger diameter tanks design, supply fabrication, erection, and testing of field erected welded steel storage tanks complete with accessories as specified herein and as shown on attached datasheets and/or drawings.

API 650 larger diameter tanks weld tightness test: remove dirt from the API 650 larger diameter tanks weld, apply white powder emulsion, spray kerosene on the other side of the weld after drying. Because of the strong penetration of kerosene, if kerosene is sprayed after 12 hours (under low temperature conditions, the time can be extended), if the surface of the welded seam coated with white emulsion has no spots, the welded seam meets the requirements.